A federal pipeline safety office investigation says the Trans-Alaska Pipeline poses a risk to public safety and the environment, and that issues tied to corrosion, inspection and pipeline restarts after shutdowns must be addressed.

The Pipeline and Hazardous Materials Safety Administration handed Alyeska Pipeline Service Co. a list of proposed corrective measures tied to challenges that have spun off from having too little oil in the 48-inch diameter, 800-mile pipeline.

The pipeline currently operates at less than one-third capacity from its peak of 2.1 million barrels per day. Less through-put means decreased crude oil temperatures and conditions that lead to corrosion.